The document details the anatomy and function of the brain's ventricles and cerebrospinal fluid (CSF). It describes the structure of the ventricular system, the production and circulation of CSF, and highlights the brain's blood supply through the Circle of Willis. The text also outlines the major subarachnoid cisterns and the organization of the brain's lobes, gyri, and sulci.

1. DR SAKHER AL-KHADERI
CONSULTANT RADIOLOGIST AMC
BRAIN CT ANATOMY AND BASIC INTERPRETATION
PART II

2. VENTRICLES

3. OBJECTIVES
 Illustrate and describe the ventricles.
 Describe the structure of the ventricles.
 Illustrate and describe the cerebrospinal
fluid (CSF) formation, absorption and
circulation.

4. VENTRICLES(Ventricular System)
 A ventricle is an internal
cavity of the brain.Within
the brain, which is filled
with cerebrospinal
fluid(CSF).
 The ventricular system is
composed of two lateral
ventricles and two midline
ventricles( third and
fourth ventricles).

5. VENTRICLES(Ventricular System)
 The chambers are
connected to allow the
flow of cerebrospinal fluid
via two interventricular
foramen (referred to as the
foramen of Monro) and
the cerebral aqueduct
(referred to as the
aqueduct of Sylvius).

6. Lateral view to show the ventricular system of the CNS
Central canal of
medulla
oblongata &
spinal cord
Fourth ventricle
Lateral ventricle
Third ventricle
Interventricular
foramen (Monro)
Cerebral
aqueduct

7. VENTRICLES(Ventricular System)
CONSISTS OF :
1) Lateral ventricle
2) Third ventricle
3) Fourth ventricle
4) Central canal of the
medulla oblongata
& spinal cord

10. LateralVentricles
 The lateral ventricles
are two curved shaped
cavities located within
the cerebrum.
 The lateral ventricles
are separated by the
septum pellucidum and
do not communicate
directly

11. Lateral ventricle
Frontal lobe
Parietal lobe
Temporal lobe
Occipital lobe

12.  C-shaped cavity & may be divided into :
2. Anterior
horn
1. Body
3. Posterior
horn
4. Inferior
horn
Third
ventricle
Fourth
ventricle
Lateral view of the ventricular cavities of the brain
Lateral ventricle

13. Anterior horn
Inferior horn
Posterior horn
Lateral view to show the ventricular system of the CNS

14.  The third ventricle is a narrow cavity or a slitlike cleft between the 2
thalamus
 Communicates ;
●
Anteriorly with lateral ventricles through interventricular
foramina (of monro)
●
Posteriorly with fourth ventricle through cerebral aqueduct (of
sylvius)
Posterior view to show the ventricular system of the CNS
Third ventricle

15. Frontal lobe
Parietal lobe
Temporal lobe
Occipital lobe
Third ventricle

16. Third
ventricle
Hypothalamus
Coronal section of the brain (posterior view)
Third ventricle
Thalamus
ROOF
FLOOR
Lateral wall
Body of fornix

17. Fourth ventricle
 The fourth ventricle Is a
rhomboid or diamond
shaped cavity.
 It is a wide and flattened
space located just anterior
to the cerebellum and
posterior to the upper, or
superior, half of the medulla
oblongata and the pons.

18. Cerebellum
Pons
Medulla
oblongata
(superior
half)
Sagittal section of the 4th ventricle
Cerebral
aqueduct
Central
canal
(spinal
cord)
Fourth ventricle
Fourth
ventricle
ANTERIOR
POSTERIOR

19. Frontal lobe
Parietal lobe
Temporal lobe
Occipital lobe
Fourth ventricle

20. Pons
Medulla
oblongata
(superior
half)
Fig. : Sagittal section of the 4th ventricle
Cerebral
aqueduct
ANTERIOR
POSTERIOR
Superior part of the roof ;
Superior medullary velum
Inferior part of the roof ;
Inferior medullary velum
Roof or posterior wall of fourth
ventricle :

21. CENTRAL CANAL
 Opens superiorly into the fourth ventricle
Fourth
ventricle
Inferior ½ of
medulla
oblongata
Entire
length of
spinal cord
Central canal
(Lined with
ependyma but no
choroid plexus in the
central canal)
Extends ;

22. Frontal lobe
Parietal lobe
Temporal lobe
Occipital lobe
CENTRAL CANAL

23. Conus medullaris-
Terminal ventricle

24. CEREBROSPINAL FLUID

25. CHOROID PLEXUS
 It is formed by invaginating of
vascular pia mater into the
ventricular cavity
 It becomes highly convoluted &
produce a spongy-like
appearance
 It enters the 3rd and 4th
ventricles through their roofs,
and the lateral ventricles
through the choroid fissure
 produces cerebrospinal fluid
(CSF)
Lateral ventricle
Third ventricle
Fourth
ventricle

26. What is cerebrospinal fluid (CSF) ?
• Clear, colorless fluid
• Produced by the choroid plexus
• Found in the :
– Ventricles of the brain
– Subarachnoid space (between Arachnoid + Pia mater) around the brain & spinal cord
 The pressure of the CSF is kept remarkably constant.
 Based on the Monro-Kellie doctrine :
 “Volume of BLOOD, CSF & BRAIN at any time must be
relatively constant”

27. Physical characteristics and composition of
the CSF
Appearance Clear and colourless
Volume 130 ml
Rate of production 0.5 ml/min
Pressure 60-150 mm of water
Composition
protein 15-45 mg/100 ml
glucose 50-85 mg/ 100 ml
chloride 720-750 mg/100 ml
No. of cells 0-3 lymphocytes/cu mm

28. Function of the CSF :
1. Cushions & protects the CNS from trauma
2. Provides mechanical buoyancy & support for the brain
3. Serves as a reservoir & assists in the regulation of the
contents of the skull
4. Nourishes the CNS
5. Removes metabolites from the CNS
6. Serves as a pathway for pineal secretions to reach the
pituitary gland

29. Sites of formation :
1. Choroid plexus of the ventricle cavities, mostly is formed
in the LATERALVENTRICLES
2. Some originate from the ependymal cells lining the
ventricles
3. Some from the brain substances through perivascular
spaces
Movement of CSF inside the ventricle is controlled
by the:
1. Pulsation of the artery in the choroid plexus
2. By the aid of the cilia & microvilli of the ependymal
cells

30. cerebrospinal fluid (CSF)
 The CSF is formed in the lateral
ventricles escapes by the foramen of
monro into the third ventricle
 From the third ventricle by the aqueduct
into the fourth ventricle.
 Then from the fourth ventricle the fluid
is poured into the subarachnoid spaces
through the medial foramen of
majendie and the two lateral foramina
of luschka.
 There is no evidence that functional
communications between the cerebral
ventricles and the subarachnoid spaces
exist in any region except from the
fourth ventricle.

31. Choroid plexus of the
lateral ventricle
Site of formation
1. Lateral ventricle
2.Third ventricle
Interventricular foramina
3. Fourth ventricle
Cerebral aqueduct
3.2 Lateral
foramina
(Luschka)
3.1 Median
foramen
(Magendie)
3.2 Lateral
foramina
(Luschka)
4. Subarachnoid space
Inferiorly
Superiorly
Absorbed
Superiorly
Absorbed

32. Median sagittal section to show the subarachnoid cisterns &
circulation of CSF
Superior
cistern
Interpeduncular
cistern
Cerebellomedullary
cistern
Chiasmatic
cistern
Pontine
cistern
Circulation of CSF in subarachnoid space :
Median
foramen of
4th ventricle

33. Factors that facilitate the flow of CSF in
subarachnoid space ;
– Pulsation of the cerebral & spinal arteries
– Movements of the vertebral column
– Respiration & coughing
– Changing of the positions

34. Absorption of CSF into dural venous sinuses
 Main sites - arachnoid villi (project
into dural venous sinuses, especially,
superior sagittal sinus)
 Arachnoid villi are covered by
endothelium of the venous sinus
 Arachnoid villi tend to be grouped
together & form elevations known as
arachnoid granulations
 CSF pressure >> the pressure in the
sinus
 The rate of absorption of CSF
through the arachnoid villi controls
the CSF pressure

36. BLOOD SUPPLY OFTHE
BRAIN

37. OBJECTIVES
 Illustrate and describe the formation of the
circle of willis
 Describe the blood supply of the brain
 Arterial supply
 Venous drainage

38. Blood Supply ofThe Brain
 The brain receives it
arterial supply from
two pairs of vessels,
the vertebral and
internal carotid
arteries which are
interconnected in the
cranial cavity to
produce an arterial
circle (ofWillis).

39. Internal carotid artery

40. Internal Carotid Artery
 Begins – bifurcation of Com Carotid A
 Perforates base of skull – carotid canal
 Enters middle cranial fossa beside dorsum sellae
 In the cavernous sinus
 Horizontal
 Emerge out – medial side of Ant clinoid process – perforates dura &
arachnoid mater – enters subarachnoid space
 Turns posteriorly – below optic nerve
 Turns upward – lateral to optic chiasma
 Now is under anterior perforated susbtance
 Divides – into ANTERIOR & MIDDLE cerebral arteries

41. Vertebral Artery
 Branch of first part of subclavian A
 Passes – foramen transvesarium C6 – C1
 Enters through foramen magnum – perforates dura &
arachnoid mater – enters subarachnoid space
 Turns upward, forward, medially – medulla oblongata
 Lower border of pons – joins opposite side
 BASILAR artery

42. Blood Supply ofThe Brain
 VERTEBRAL
 Basilar
 Posterior cerebral
artery
 INTERNAL CAROTID
 Middle cerebral
 Anterior cerebral
 Anterior communicating
artery
 Posterior communicating
artery
CIRCLE OFWILLIS

43. Branches of :-
 VERTEBRAL
 Basilar
 PCA
 Pontine
 Labyrinthine
 Ant Inf CA
 Sup cerebellar
 Choroidal
 INTERNAL CAROTID
 ACA
 MCA
 Ophthalmic
 Ant ComA
 Post Com A
 Choroidal

44. Circle of Willis
 Interpeduncular fossa –
base of brain
 Anastomosis
 2 internal carotid
arteries
 2 vertebral arteries
 In the subarachnoid
space

45. Vertebral arteries
BasilarA
Posterior cerebral
artery
Posterior
communicating
artery
Internal
carotid
artery
Middle cerebral
artery
Anterior cerebral
artery
Anterior
communicating
artery
Post Inf cerebellarA
Sup cerebellarA
Ant Inf cerebellar A

46. Middle cerebral artery
Anterior cerebral artery
Posterior cerebral artery

47. MIDDLE CEREBRAL ARTERY
LOBE AREA
FRONTAL Motor – except for paracentral lobule
Motor speech – esp left side
PARIETAL Sensory – except for paracentral lobule
Sensory speech
TEMPORAL Auditory

48. POSTERIOR CEREBRAL ARTERY
LOBE AREA
OCCIPITAL Visual
TEMPORAL Olfactory

49. ARTERIES to specific brain areas
Corpus striatum Middle & lateral
striate
Anterior & Middle
cerebral artery
Internal capsule
Thalamus PComA, basilar, PCA
Midbrain PCA, supCerebellarA, basilar
Pons Basilar, Ant, inf, supCerebellarA,
Medulla oblongata Vertebral, ASA,PSA,PICA, basilar
Cerebellum supCerebellar, AICA,PICA

50. VEIN of specific areas
Midbrain Basal, great cerebral
Pons Basal, cerebellar
Medulla oblongata Anterior & posterior spinal
Cerebellum Great cerebral

51. Superior sagittal sinus
Inferior sagittal sinus
Straight
sinus
Superior cerebral vein
Medial aspect of
hemisphere
Great
cerebral
vein
Transverse sinus
(R & L)
Sigmoid sinus
(R & L)
Confluence of
sinus
IntJugular
vein
IntJugular
vein
Cavernous sinus
Middle cerebral vein
Inferior
petrosal
sinus
Superior
petrosal
sinus

52. The subarachnoid cisterns are areas within the
subarachnoid space where the pia mater and
arachnoid membrane are not in close
approximation.The subarachnoid tissue is not as
abundant here as in the normal subarachnoid
space and cerebrospinal fluid (CSF) gathers to
form pools or cisterns (Latin: "box").
Some major subarachnoid cisterns:
cisterna magna (cerebellomedullary cistern): the
largest of the subarachnoid cisterns
pontine cistern
suprasellar cistern
interpeduncular cistern
quadrigeminal cistern (superior cistern or cistern
of the great cerebral vein)
ambient cistern

53.  Sulcus : A sulcus is depression or fissure in the
surface of the brain. ( valleys )
 Gyrus : A gyrus is a ridge on the cerebral
cortex. It is generally surrounded by one or
more sulci ( hills )

54. Typical continous fissure
Interhemispheric fissure
Sylvian fissure ( lateral sulcus )
Parieto-occipital fissure
Collateral sulcus
Central sulcus
Calcarine Sulcus

55. Interhemispheric fissure
Deep sulcus upto
corpus collosum
Divides brain into
two hemisphere

56. Sylvian fissure
deep, mostly
horizontal
insula is buried
within it
separates temporal
lobe from parietal
and frontal lobes

57. Parieto - occipital fissure
very deep
oftenY-shaped from
sagittal view
X-shaped in
horizontal and
coronal views

58. Collateral sulcus
Divides lingual and
parahippocampal
gyri from fusiform
gyrus.

59. Central sulcus
usually freestanding
(no intersections)
Seperates frontal
and parietal lobe.

60. Calcarine sulcus

61. Lobes of brain
Frontal lobe.
Parietal lobe.
Temporal lobe.
Occipital lobe.
Limbic lobe.
Insular lobe.

62. • Frontal lobe:
Anterior region of hemisphere; anterior to central sulcus,
superior to sylvian fissure
• Parietal lobe:
Posterior region of hemisphere; posterior to central sulcus,
anterior to parietooccipital sulcus
• Occipital lobe:
Posterior to parietooccipital sulcus
• Temporal lobe:
Inferior to sylvian fissure, anterior to angular gyrus

64. Lateral surface of brain

65. Medial surface of brain

66. Basal surface of brain

67. B R A I N
CTANATOMY

85. THE END